Nova1介导的UPR和PPARγ通路基因转录后调控在脂肪细胞分化中的作用研究

The differentiation of adipose-derived stem cells is critically important in the material metabolism and energy balance of the body. RNA binding proteins mediated gene post-transcriptional regulation are important in the differentiation of stem cells. We found for the first time that NOVA1, a RNA binding protein, plays critical roles in the adipogenesis of adipose-derived stem cells. Gene expression analysis and CLIP-Seq analysis revealed that NOVA1 regulate genes involved in ER stress and adipose synthesis. To uncover the post transcriptional mechanism of NOVA1 in the regulation of unfolded protein response (UPR) and PPARγ signal which regulates adipogenesis, we will firstly study the regulation of NOVA1 on the splicing and stability of genes related to UPR and PPARγ signal. Then we will study the post transcriptional regulation on the activation of UPR and PPARγ signal pathway and their roles in adipogenesis and lipid metabolism. Finally, we will verify the regulation of NOVA1 in UPR and adipogenesis in NOVA1 knock out mouse. This project would make great contribution to the differentiation of stem cells, which would shed light on treatment of metabolism abnormality.

脂肪细胞分化对于机体物质代谢和能量平衡具有重要意义。RNA结合蛋白介导的基因转录后调控在干细胞分化中发挥重要功能。我们在前期研究中首次发现RNA结合蛋白—NOVA1在脂肪间充质干细胞成脂分化过程中有重要作用，基因表达谱芯片和CLIP-Seq研究发现NOVA1调控大量未折叠蛋白反应(UPR)和PPARγ通路相关基因。为明确NOVA1如何通过UPR和PPARγ通路相关基因的转录后调控进而影响脂肪细胞分化，本课题将首先分析NOVA1对UPR和PPARγ通路相关基因的剪接和稳定性调控，继而阐明其对UPR应答和PPARγ通路活化程度的影响以及其在成脂分化中的作用，最后应用NOVA1敲除小鼠验证NOVA1对脂肪细胞分化和脂代谢的影响，以及UPR和PPARγ通路基因的转录后调控在脂肪细胞分化与脂代谢中的作用。本研究将对脂肪细胞分化调控机制研究取得重要突破，并为脂肪代谢异常疾病的治疗提供参考。

脂肪组织作为体内最大的内分泌器官，参与机体多项重要的生理过程，如能量代谢、免疫、炎症反应等。人类白色脂肪分化的分子机制尚未完全阐明。深入探讨白色脂肪生成过程中间充质干细胞成脂分化的调控机制对于完善脂肪发育相关理论及脂肪相关疾病的防治都具有重大意义。RNA结合蛋白介导的选择性剪接等转录后调控机制在干细胞定向分化过程中具有重要功能。本课题发现RNA结合蛋白NOVA1是人间充质干细胞脂肪分化所必需的，通过探讨NOVA1-RNA相互作用，首次证明成脂过程中，NOVA1通过调节DNAJC10的剪接和蛋白表达，防止内质网应激过度激活；并且，NOVA1发挥维持NCOR2的剪接和表达、促进脂质代谢基因位点的染色质可及性的作用。此外，NOVA1 对人类白色脂肪形成的这些影响在小鼠体内无法重现，多物种基因组和转录组比较分析表明，NOVA1靶向RNA剪接具有物种差异。该项目成果的创新性强，为NOVA1在白色脂肪形成过程中协调剪接和细胞器功能的物种特异性作用提供了证据。